Investigator Lance Badger from the Santa Rosa police department shows Andy Lopez's toy replica gun (left) in comparison to an AK 47 assault style weapon (right) at a press conference in the community center in Santa Rosa, California, on Wednesday, October 23, 2013.

Photo: Liz Hafalia, The Chronicle

Investigator Lance Badger from the Santa Rosa police department...

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Alejandra Lopez put her sentiments on a sign Tuesday October 29, 2013 in Santa Rosa, Calif. A rally and march to express outrage over the fatal shooting of Andy Lopez Cruz by a Sonoma County sheriff's deputy ended outside the Sheriff's headquarters.

Photo: Brant Ward, The Chronicle

Alejandra Lopez put her sentiments on a sign Tuesday October 29,...

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Brissa Gonzalez, 14, holds up her phone which has been adorned with a custom cover with Andy Lopez's photograph during a "Justice for Andy Lopez" rally and march October 29, 2013 in Santa Rosa, Calif. Hundreds rallied at the Old Courthouse Square and marched to Santa Rosa Junior College, gave speeches and then marched on en masse down the middle of Mendocino Ave to the Sheriff's Department where there were speeches and chanting. Andy Lopez Cruz, 15 was killed on Oct. 22 by a Sonoma County Sheriff's Deputy just outside of Santa Rosa when he was spotted carrying a toy rifle.

Photo: Leah Millis, The Chronicle

Brissa Gonzalez, 14, holds up her phone which has been adorned with...

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Many in the crowd of over 1000 expressed their feelings on signs Tuesday October 29, 2013 in Santa Rosa, Calif. A rally and march to express outrage over the fatal shooting of Andy Lopez Cruz by a Sonoma County sheriff's deputy ended outside the Sheriff's headquarters.

Photo: Brant Ward, The Chronicle

Many in the crowd of over 1000 expressed their feelings on signs...

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A protestor carries a photo of Andy Lopez Cruz, 13, on a march protesting his death in Santa Rosa, Calif., on Friday, October 25, 2013. The eighth-grader was killed by police while walking near his home carrying a toy rifle.

In this photo provided by the Lopez family is a picture of Andy Lopez, who was killed by sheriff's deputies in Santa Rosa, Calif. Tuesday, Oct. 22, 2013. Northern California sheriff's deputies have shot and killed the 13-year-old boy after repeatedly telling him to drop what turned out to be a replica assault rifle, sheriff's officials and family members said. Two Sonoma County deputies on patrol saw the boy walking with what appeared to be a high-powered weapon.

The Sonoma County sheriff's deputy who shot and killed a 13-year-old boy after mistaking his toy AK-47 for a real rifle pulled a gun on a motorist twice during a traffic stop on Highway 101 about two months earlier, the driver said Thursday.

Jeff Westbrook of Santa Rosa said he was mistreated by Deputy Erick Gelhaus after being pulled over Aug. 21 in Cotati for failing to signal a lane change in his BMW. The interaction troubled Westbrook so much that he recalled asking Gelhaus at one point, "Sir, is there something wrong with you?"

"I felt like I was watching somebody I needed to help," said Westbrook, 57, a program manager at an information technology company. "This was not right. He did not manage this correctly."

Gelhaus is on routine paid leave after the Oct. 22 shooting of eighth-grader Andy Lopez Cruz, who was walking with a replica AK-47 pellet gun near his home just outside Santa Rosa. His attorney declined Thursday to comment on Westbrook's allegations.

Gelhaus, who joined the sheriff's office 24 years ago, is a gun expert - an Iraq War veteran and hunter who serves as a field training officer and weapons instructor.

He told investigators he shot Andy because he thought the pellet gun was real and because he felt threatened when the boy turned toward him.

But Andy's friends and relatives believe the deputy overreacted and did not give the boy a chance to put the gun down.

Westbrook said he had hoped to meet with Gelhaus last week to clear the air about what happened during the traffic stop.

He said he had already discussed the incident with Gelhaus' supervisor, telling the sergeant he had concerns about the deputy's "emotional stability."

But a day after Andy was killed, Westbrook received an e-mail from Gelhaus' supervisor saying the deputy would be out of the office "due to unforeseen circumstances."

"Now I find out a child is involved. I am such an irrelevant part of this thing," Westbrook said. "I am devastated. I'm terribly shocked. I'm appalled."

Westbrook said he is now wondering whether he should have pressed his complaints.

"I'm struggling with that now," Westbrook said. "I'm wondering, if I had fought this a little more aggressively - actually waved around like a chimpanzee with my arms in the air to the district attorney's office and come down there physically - that maybe something could have changed. I don't know."

Assistant Sheriff Lorenzo Duenas said Thursday that he could not discuss Westbrook's traffic stop because it was a personnel issue and part of an internal investigation.

Westbrook said he and a colleague were traveling south on Highway 101 near Highway 116 when Gelhaus pulled them over and then approached the BMW on the passenger side.

There wasn't much room on the side of the highway, Westbrook said, so he rolled down his window and offered to move the car. That's when Gelhaus pulled a gun on him and yelled at him to turn the car off, Westbrook said. He said he responded that the car was already off.

According to Westbrook, Gelhaus returned to his cruiser to write a ticket. Several minutes later, the driver said, Gelhaus asked him to walk back to his cruiser and then pulled a gun on him a second time, asking him if he had any weapons before frisking him.

Westbrook said he finally asked the deputy why he had pulled him over, with Gelhaus referring to an illegal lane change. Westbrook said that's when he asked the deputy if he was OK. Gelhaus didn't answer, he said.